Blood

Published by American Society of Hematology
Online ISSN: 1528-0020
Publications
Article
In this issue of Blood, Hosking and colleagues report the lack of correlation between genetic variants within the MHC and the risk of ALL.
 
Article
In this issue of Blood, Li et al reveal the genetic elements that control the activity of Bcl11b, a critical regulator of T-cell development. Lineage-defining transcription factors (TFs), such as Bcl11b, control key steps in cellular differentiation throughout development, and understanding how these TFs are themselves regulated represents a major challenge.
 
Article
Recent data from mouse models suggest that some phenotypes of X-linked lymphoproliferative disease (XLP) result from impaired T:B-cell interactions.Hislop and colleagues now provide evidence that this may contribute to abnormal responses to Epstein-Barr virus (EBV) in XLP.
 
Article
In this issue of Blood, Lausten-Thomsen et al challenge the notion that TEL-AML1 transcripts are prevalent in newborns, raising questions about our understanding of the natural history of childhood ALL and the potential utility of newborn screening.
 
Article
Steady-state binding of ADP to blood platelets and isolated membranes has not previously been obtained because of complications arising from metabolism of the ligand and dilution due to its secretion from storage granules. In the present studies, competition binding isotherms (n = 9) using paraformaldehyde-fixed platelets showed that [2-3 H]ADP bound to two sites with a small amount (approximately 5% of total) of nonspecific binding: 410,000 +/- 40,000 sites of low affinity (Kd 7.9 +/- 2.0 mumol/L) and 160,000 +/- 20,000 sites of high affinity (Kd 0.35 +/- 0.04 mumol/L) corresponding to the ADP concentration required for activation in fresh platelets (0.1-0.5 mumol/L). All agonists and antagonists examined were able to compete with ADP at the high-affinity site. The strong platelet agonists 2-methylthio ADP and 2-(3-aminopropylthio)ADP competed with ADP at the high-affinity site with dissociation constant values of 7 mumol/L and 200 mumol/L, respectively. The partial agonist 2',3'-dialdehyde ADP and the weak agonist GDP also competed at the high-affinity site with Kd values of 5 mumol/L and 49 mumol/L, respectively. The sequence of binding affinities of other adenine nucleotides at the high-affinity site corresponded to their relative activities as known antagonists of platelet activation by ADP; namely, ADP(Kd 0.35 mumol/L) approximately equal to ATP (Kd 0.45 mumol/L) much greater than AMP (Kd 360 mumol/L). Adenosine and 2-chloroadenosine did not compete with ADP. ADP binding to the high-affinity site was inhibited by p-mercuribenzene sulfonate (Ki 250 mumol/L) but only very weakly by 5'-p-fluorosulfonylbenzoyladenosine (Ki 1 mmol/L). All the above nucleotides also competed with ADP at the low-affinity sites but, because of the high concentrations of competing nucleotide required, dissociation constants at this site were obtained only for ATP (21 mumol/L), 2-MeS ADP (200 mumol/L) and 2',3'-dialdehyde ADP (270 mumol/L). 8-Bromo ADP competed strongly with ADP at the high-affinity site (Kd 0.40 mumol/L) but weakly if at all at the low-affinity site. 8-Bromo ADP inhibited platelet activation induced by ADP (EC50 approximately 100 mumol/L) but not by collagen, thrombin, or ionophore A23187.(ABSTRACT TRUNCATED AT 400 WORDS)
 
Lack of histological evidence of thrombosis or emboli in any organ despite a hematocrit of 0.85. 
Sub-aquatic bleeding time, platelet concentrations, and bone marrow histology showing reduced megakaryocyte numbers. Sub-aquatic bleeding time was measured to assess hemostasis (A). Apparently reduced platelet numbers in transgenic mice (B) were calculated to be in the same range or even increased in comparison to wild type mice when the highly reduced 
Computerized thrombelastography of wild type and transgenic mice blood: effect of hematocrit and platelet concentration. Computerized thrombelastography was used to investigate clot formation. Native whole blood from wild type (dashed lines) and transgenic (solid lines) mice was analyzed and typical traces of the different age groups are shown (A). Clot strength was reduced as early as 1 month in transgenic mice and further declined with age compared to wild type controls. The erythrocyte concentration was increased in blood from transgenic mice, and at the same time the concentration of platelets was decreased. In order to characterize the effect on the thrombelastogram of the erythrocyte concentration separate from the effect of the platelet concentration, experiments were performed where the concentration of one cell type was kept constant while the concentration of the other was varied. Increasing the hematocrit when the platelet concentration was kept at 1000 [10 3 /μL] (B) resulted in a marked and progressive reduction of clot strength. 
Increased erythrocyte osmotic fragility and decreased activity of the plasmatic coagulation in transgenic animals. Osmotic fragility of erythrocytes from transgenic mice (B) was markedly increased from 4 months onwards compared to wild type controls (A). Prolongation of the activated partial thromboplastin time (C) and the thrombin clotting time (D) reveal a decreased activity of the plasmatic coagulation. wt wild type, tg transgenic, OD optical density. * P < 0.01, # P < 0.001, compared to age-matched wild type controls. 
Article
We have generated a transgenic mouse line that reaches a hematocrit concentration of 0.85 due to constitutive overexpression of human erythropoietin in an oxygen-independent manner. Unexpectedly, this excessive erythrocytosis did not lead to thrombembolic complications in all investigated organs at any age. Thus, we investigated the mechanisms preventing thrombembolism in this mouse model. Blood analysis revealed an age-dependent elevation of reticulocyte numbers and a marked thrombocytopenia that matched the reduced megakaryocyte numbers in the bone marrow. However, platelet counts were not different from wild-type controls, when calculations were based on the distribution (eg, plasma) volume, thereby explaining why thrombopoietin levels did not increase in transgenic mice. Nevertheless, bleeding time was significantly increased in transgenic animals. A longitudinal investigation using computerized thromboelastography revealed that thrombus formation was reduced with increasing age from 1 to 8 months in transgenic animals. We observed that increasing erythrocyte concentrations inhibited profoundly and reversibly thrombus formation and prolonged the time of clot development, most likely due to mechanical interference of red blood cells with clot-forming platelets. Transgenic animals showed increased nitric oxide levels in the blood that could inhibit vasoconstriction and platelet activation. Finally, we observed that plasmatic coagulation activity in transgenic animals was significantly decreased. Taken together, our findings suggest that prevention of thrombembolic disease in these erythrocytotic transgenic mice was due to functional consequences inherent to increased erythrocyte concentrations and a reduction of plasmatic coagulation activity, the cause of which remains to be elucidated.
 
Article
In a large study of children with acute ITP published in this issue of Blood, Neunert and colleagues find that irrespective of therapy aimed at raising the platelet count or the severity of thrombocytopenia, severe bleeding is rare.
 
Article
The association of fibroblast growth factor receptor 3 (FGFR3) expression with t(4;14) multiple myeloma (MM) and the demonstration of the transforming potential of this receptor tyrosine kinase (RTK) make it a particularly attractive target for drug development. We report here a novel and highly specific anti-FGFR3-neutralizing antibody (PRO-001). PRO-001 binds to FGFR3 expressed on transformed cells and inhibits FGFR3 autophosphorylation and downstream signaling. The antibody inhibited the growth of FGFR3-expressing FDCP cells (IC(50) of 0.5 microg/mL) but not that of cells expressing FGFR1 or FGFR2, and potently inhibited FGFR3-dependent solid tumor growth in a mouse xenograft model. Furthermore, PRO-001 inhibited the growth of the FGFR3-expressing, human myeloma cell line, UTMC2. Inhibition of viability was still observed when cells were cocultured with stroma or in the presence of IL-6 or IGF-1. PRO-001 did not inhibit constitutive activation of K650E, G384D, and Y373C FGFR3 in myeloma cell lines and failed to inhibit the growth of these cells. Most importantly, however, PRO-001 induced cytotoxic responses in primary t(4;14)(+) MM samples with an increase in apoptotic index of 20% to 80% as determined by annexin V staining. The data demonstrate that PRO-001 is a potent and specific inhibitor of FGFR3 and deserves further study for the treatment of FGFR3-expressing myeloma.
 
Progression-free survival (A) and overall survival (B) in response evaluable patients (n=257) treated with single-agent carfilzomib. 
Responses according to demographic and baseline disease characteristics. 
Article
Carfilzomib is a next-generation, selective proteasome inhibitor being evaluated for the treatment of relapsed and refractory multiple myeloma. In this open-label, single-arm phase 2 study (PX-171-003-A1), patients received single-agent carfilzomib 20 mg/m(2) intravenously twice weekly for 3 of 4 weeks in cycle 1, then 27 mg/m(2) for ≤ 12 cycles. The primary endpoint was overall response rate (≥ partial response). Secondary endpoints included clinical benefit response rate (≥ minimal response), duration of response, progression-free survival, overall survival, and safety. A total of 266 patients were evaluable for safety, 257 for efficacy; 95% were refractory to their last therapy; 80% were refractory or intolerant to both bortezomib and lenalidomide. Patients had median of 5 prior lines of therapy, including bortezomib, lenalidomide, and thalidomide. Overall response rate was 23.7% with median duration of response of 7.8 months. Median overall survival was 15.6 months. Adverse events (AEs) were manageable without cumulative toxicities. Common AEs were fatigue (49%), anemia (46%), nausea (45%), and thrombocytopenia (39%). Thirty-three patients (12.4%) experienced peripheral neuropathy, primarily grades 1 or 2. Thirty-three patients (12.4%) withdrew because of an AE. Durable responses and an acceptable tolerability profile in this heavily pretreated population demonstrate the potential of carfilzomib to offer meaningful clinical benefit. This trial was registered at www.clinicaltrials.gov as #NCT00511238.
 
Article
Carfilzomib is a selective proteasome inhibitor that binds irreversibly to its target. In phase 1 studies, carfilzomib elicited promising responses and an acceptable toxicity profile in patients with relapsed and/or refractory multiple myeloma (R/R MM). In the present phase 2, multicenter, open-label study, 129 bortezomib-naive patients with R/R MM (median of 2 prior therapies) were separated into Cohort 1, scheduled to receive intravenous carfilzomib 20 mg/m(2) for all treatment cycles, and Cohort 2, scheduled to receive 20 mg/m(2) for cycle 1 and then 27 mg/m(2) for all subsequent cycles. The primary end point was an overall response rate (≥ partial response) of 42.4% in Cohort 1 and 52.2% in Cohort 2. The clinical benefit response (overall response rate + minimal response) was 59.3% and 64.2% in Cohorts 1 and 2, respectively. Median duration of response was 13.1 months and not reached, and median time to progression was 8.3 months and not reached, respectively. The most common treatment-emergent adverse events were fatigue (62.0%) and nausea (48.8%). Single-agent carfilzomib elicited a low incidence of peripheral neuropathy-17.1% overall (1 grade 3; no grade 4)-in these pretreated bortezomib-naive patients. The results of the present study support the use of carfilzomib in R/R MM patients. This trial is registered at www.clinicaltrials.gov as NCT00530816.
 
Article
Combination studies of histone deacetylase inhibitors (HDACi) and proteasome inhibitors are providing preclinical framework to build better strategies against hematologic malignancies. Our previous work found that a novel proteasome inhibitor, NPI-0052, and HDACi synergistically induce apoptosis in leukemia cells in a caspase-8- and oxidant-dependent manner. Here we extend those observations to primary leukemia cells and identify novel mechanisms of synergy. Because the proximal targets of NPI-0052 and HDACi are inhibition of proteasome activity and histone acetylation, we initially examined those biochemical events. Increased acetylation of histone-H3 was detected in Jurkat and CLL primary cells treated with NPI-0052, alone or in combination with various HDACi (MS/SNDX-275 or vorinostat). Hyperacetylation by NPI-0052 occurred to a lesser extent in caspase-8-deficient cells and in cells treated with an antioxidant. These results indicate that NPI-0052 is eliciting caspase-8 and oxidative stress-dependent epigenetic alterations. In addition, real-time PCR revealed that MS/SNDX-275 repressed expression of the proteasomal beta5, beta2, and beta1 subunits, consequently inhibiting respective enzymatic activities. Overall, our results suggest that crosstalk by NPI-0052 and HDACi are contributing, along with caspase-8 activation and oxidative stress, to their synergistic cytotoxic effects in leukemia cells, reinforcing the potential clinical utility of combining these 2 agents.
 
Article
Our recent study demonstrated that a novel proteasome inhibitor NPI-0052 is distinct from bortezomib (Velcade) and, importantly, triggers apoptosis in multiple myeloma (MM) cells resistant to bortezomib. Here we demonstrate that combining NPI-0052 and lenalidomide (Revlimid) induces synergistic anti-MM activity in vitro using MM-cell lines or patient MM cells. NPI-0052 plus lenalidomide-induced apoptosis is associated with (1) activation of caspase-8, caspase-9, caspase-12, caspase-3, and poly(ADP) ribose polymerase; (2) activation of BH-3 protein BIM; (3) translocation of BIM to endoplasmic reticulum; (4) inhibition of migration of MM cells and angiogenesis; and (5) suppression of chymotrypsin-like, caspase-like, and trypsin-like proteasome activities. Importantly, blockade of BIM using siRNA significantly abrogates NPI-0052 plus lenalidomide-induced apoptosis. Furthermore, studies using biochemical inhibitors of caspase-8 versus caspase-9 demonstrate that NPI-0052 plus lenalidomide-triggered apoptosis is primarily dependent on caspase-8 signaling. In animal tumor model studies, low-dose combination of NPI-0052 and lenalidomide is well tolerated, significantly inhibits tumor growth, and prolongs survival. Taken together, our study provides the preclinical rationale for clinical protocols evaluating lenalidomide together with NPI-0052 to improve patient outcome in MM.
 
Article
Our recent study demonstrated that a novel proteasome inhibitor NPI-0052 triggers apoptosis in multiple myeloma (MM) cells, and importantly, that is distinct from bortezomib (Velcade) in its chemical structure, effects on proteasome activities, and mechanisms of action. Here, we demonstrate that combining NPI-0052 and bortezomb induces synergistic anti-MM activity both in vitro using MM cell lines or patient CD138(+) MM cells and in vivo in a human plasmacytoma xenograft mouse model. NPI-0052 plus bortezomib-induced synergistic apoptosis is associated with: (1) activation of caspase-8, caspase-9, caspase-3, and PARP; (2) induction of endoplasmic reticulum (ER) stress response and JNK; (3) inhibition of migration of MM cells and angiogenesis; (4) suppression of chymotrypsin-like (CT-L), caspase-like (C-L), and trypsin-like (T-L) proteolytic activities; and (5) blockade of NF-kappaB signaling. Studies in a xenograft model show that low dose combination of NPI-0052 and bortezomib is well tolerated and triggers synergistic inhibition of tumor growth and CT-L, C-L, and T-L proteasome activities in tumor cells. Immununostaining of MM tumors from NPI-0052 plus bortezomib-treated mice showed growth inhibition, apoptosis, and a decrease in associated angiogenesis. Taken together, our study provides the preclinical rationale for clinical protocols evaluating bortezomib together with NPI-0052 to improve patient outcome in MM.
 
NPI-0052 inhibits both inducible and constitutive NF-B activation in a dose-and time-dependent manner. (A) KBM-5 cells were incubated with the indicated concentrations of NPI-0052 for 4 hours and then exposed to 0.1 nM TNF for 30 minutes. The nuclear extracts were subjected to EMSA to evaluate NF-B activation. (B) Cells were preincubated with 50 nM NPI-0052 for the indicated times, treated with 0.1 nM TNF for 30 minutes, and then subjected to EMSA to evaluate NF-B activation. H1299 (C) or A293 (D) cells were pretreated with 50 nM NPI-0052 for 4 hours and then treated with 0.1 nM TNF for 30 minutes. The nuclear extracts were then prepared and assayed for NF-B by EMSA as described in "Materials and methods." (E) U266 cells with constitutive NF-B activation cells were incubated with () 50 nM NPI-0052 for 12 hours. Nuclear extracts were prepared and analyzed for NF-B activation by EMSA.
NPI-0052 inhibits TNF-induced NF-B-dependent reporter gene (SEAP) expression and suppresses chymotrypsin-like activity of 20S proteasome. (A) A293 cells were transiently transfected with an NF-B-containing plasmid linked to the SEAP gene and then pretreated with the indicated concentrations of NPI-0052 for 4 hours. After 24 hours in culture with 1 nM TNF, cell supernatants were collected and assayed for SEAP activity as described in "Materials and methods." Results are expressed as fold activity over the activity of the vector control. (B) Chemical structures of various proteasome inhibitors. (C) KBM-5 (1 10 6 ) cells were incubated with 50 nM each of various proteasome inhibitors for 4 hours and then exposed to 0.1 nM TNF for 30 minutes. The nuclear extracts were subjected to EMSA to evaluate NF-B activation. (D) RPMI 8226 and PC-3 cells were treated with various concentrations of NPI-0052 and bortezomib for 1 hour, prepared the cell lysates, and assayed for the chymotrypsin-like activity of the 20S proteasome as described in "Materials and methods." Results are presented as percentage inhibition compared with the chymotrypsin-like activity observed in untreated cells. Error bars represent SD of triplicate values.
KBM-5 cells treated with NPI-0052, TNF, thalidomide, and bortezomib alone or in combination
U266 cells treated with NPI-0052, thalidomide, and bortezomib alone or in combination
Article
Salinosporamide A (also called NPI-0052), recently identified from the marine bacterium Salinispora tropica, is a potent inhibitor of 20S proteasome and exhibits therapeutic potential against a wide variety of tumors through a poorly understood mechanism. Here we demonstrate that salinosporamide A potentiated the apoptosis induced by tumor necrosis factor alpha (TNF), bortezomib, and thalidomide, and this correlated with down-regulation of gene products that mediate cell proliferation (cyclin D1, cyclooxygenase-2 [COX-2], and c-Myc), cell survival (Bcl-2, Bcl-xL, cFLIP, TRAF1, IAP1, IAP2, and survivin), invasion (matrix metallopro-teinase-9 [MMP-9] and ICAM-1), and angiogenesis (vascular endothelial growth factor [VEGF]). Salinosporamide A also suppressed TNF-induced tumor cell invasion and receptor activator of nuclear factor kappaB ligand (RANKL)-induced osteoclastogenesis. We also found that it suppressed both constitutive and inducible NF-kappaB activation. Compared with bortezomib, MG-132, N-acetyl-leucyl-leucyl-norleucinal (ALLN), and lactacystin, salinosporamide A was found to be the most potent suppressor of NF-kappaB activation. Further studies showed that salinosporamide A inhibited TNF-induced inhibitory subunit of NF-kappaB alpha (IkappaBalpha) degradation, nuclear translocation of p65, and NF-kappaB-dependent reporter gene expression but had no effect on IkappaBalpha kinase activation, IkappaBalpha phosphorylation, or IkappaBalpha ubiquitination. Thus, overall, our results indicate that salinosporamide A enhances apoptosis, suppresses osteoclastogenesis, and inhibits invasion through suppression of the NF-kappaB pathway.
 
Article
The proteasome has been successfully targeted for the treatment of multiple myeloma and mantle cell lymphoma; however, in other hematologic malignancies, bortezomib has been less effective as a single agent. Here, we describe effects of NPI-0052, a novel proteasome inhibitor, in leukemia model systems. In cell lines, NPI-0052 inhibits all 3 proteolytic activities associated with the proteasome: chymotrypsin-, trypsin-, and caspase-like. NPI-0052 also induces DNA fragmentation in leukemia lines and in mononuclear cells from a Ph + acute lymphoblastic leukemia (ALL) patient. Caspase-3 activation by NPI-0052 was seen in wild-type Jurkat cells, but was significantly lessened in Fas-associated death domain (FADD)-deficient or caspase-8-deficient counterparts. NPI-0052-induced apoptosis was further probed using caspase-8 inhibitors, which were more protective than caspase-9 inhibitors. N-acetyl cysteine (NAC) also conferred protection against NPI-0052-induced apoptosis, indicating a role for oxidative stress by NPI-0052. In support of the drug's in vitro activities, biweekly treatment with NPI-0052 lessened total white blood cell (WBC) burden over 35 days in leukemic mice. Interestingly, combining NPI-0052 with either MS-275 or valproic acid (VPA) induced greater levels of cell death than the combination of bortezomib with these histone deacetylase inhibitors (HDACi). These effects of NPI-0052, alone and in combination with HDACi, warrant further testing to determine the compound's clinical efficacy in leukemia.
 
Study treatment disposition MPD cohort (n 5 52) Overall (N 5 84) 
Treatment-emergent adverse events occurring in ‡25% of patients for any grade or ‡5% for grade 3/4 in the MPD cohort or overall study population 
Article
We previously reported a phase 1b dose-escalation study of carfilzomib, lenalidomide, and low-dose dexamethasone (CRd) in relapsed or progressive multiple myeloma where the maximum planned dose (MPD) was carfilzomib 20 mg/m2 days 1 and 2 of cycle 1 and 27 mg/m2 days 8, 9, 15, 16, and thereafter; lenalidomide 25 mg days 1 to 21; and dexamethasone 40 mg once weekly on 28-day cycles. Herein, we present results from the phase 2 dose expansion at the MPD, focusing on the 52 patients enrolled in the MPD cohort. Median follow-up was 24.4 months. In the MPD cohort, overall response rate (ORR) was 76.9% with median time to response of 0.95 month (range, 0.5-4.6) and duration of response (DOR) of 22.1 months. Median progression-free survival was 15.4 months. ORR was 69.2% in bortezomib-refractory patients and 69.6% in lenalidomide-refractory patients with median DOR of 22.1 and 10.8 months, respectively. A median of 9.5 (range, 1-45) carfilzomib cycles were started with 7.7% of patients requiring carfilzomib dose reductions and 19.2% discontinuing CRd due to adverse events (AEs). Grade 3/4 AEs included lymphopenia (48.1%), neutropenia (32.7%), thrombocytopenia (19.2%), and anemia (19.2%). CRd at the MPD was well tolerated with robust, rapid, and durable responses.
 
Article
Neutralizing the interaction of the platelet receptor gpIb with VWF is an attractive strategy to treat and prevent thrombotic complications. ALX-0081 is a bivalent Nanobody which specifically targets the gpIb-binding site of VWF and interacts avidly with VWF. Nanobodies are therapeutic proteins derived from naturally occurring heavy-chain-only Abs and combine a small molecular size with a high inherent stability. ALX-0081 exerts potent activity in vitro and in vivo. Perfusion experiments with blood from patients with acute coronary syndrome on standard antithrombotics demonstrated complete inhibition of platelet adhesion after addition of ALX-0081, while in the absence of ALX-0081 residual adhesion was observed. In a baboon efficacy and safety model measuring acute thrombosis and surgical bleeding, ALX-0081 showed a superior therapeutic window compared with marketed antithrombotics. Pharmacokinetic and biodistribution experiments demonstrated target-mediated clearance of ALX-0081, which leads to a self-regulating disposition behavior. In conclusion, these preclinical data demonstrate that ALX-0081 combines a high efficacy with an improved safety profile compared with currently marketed antithrombotics. ALX-0081 has entered clinical development.
 
Article
Thrombolytic therapy is the cornerstone of treatment of acute atherothrombotic ischemic stroke but is associated with brain hemorrhage; antiplatelet therapy has limited efficacy and is still associated with intracranial bleeding. Therefore, new antithrombotic approaches with a better efficacy/safety ratio are required. We have assessed the effect of ALX-0081, a Nanobody against the A1 domain of von Willebrand factor (VWF) that blocks VWF binding to GPIb, of the thrombolytic agent recombinant tissue plasminogen activator (rtPA), and of the GPIIb/IIIa antagonist tirofiban, in a middle cerebral artery (MCA) thrombosis model in guinea pigs. Drugs were administered before, immediately after, or 15 or 60 minutes after the total occlusion of the MCA. ALX-0081 prevented MCA thrombosis and induced reperfusion when given immediately after and 15 minutes after complete occlusion and reduced brain damage without inducing hemorrhage, whereas tirofiban prevented thrombosis but did not induce reperfusion and induced striking brain hemorrhage. rtPA also induced reperfusion when given 60 minutes after occlusion but provoked brain hemorrhage. Skin bleeding time was not modified or was moderately prolonged by ALX-0081, whereas tirofiban and rtPA prolonged it. The inhibition of the GPIb-VWF axis in guinea pigs prevents cerebral artery thrombosis and induces early reperfusion without provoking intracerebral bleeding thus reducing brain infarct area.
 
Article
Interactions between the protein kinase C (PKC) and Chk1 inhibitor UCN-01 and the heat shock protein 90 (Hsp90) antagonist 17-AAG have been examined in human leukemia cells in relation to effects on signal transduction pathways and apoptosis. Simultaneous exposure (30 hours) of U937 monocytic leukemia cells to minimally toxic concentrations of 17-AAG (eg, 400 nM) and UCN-01 (eg, 75 nM) triggered a pronounced increase in mitochondrial injury (ie, loss of mitochondrial membrane potential [Deltapsim]; cytosolic release of cytochrome c), caspase activation, and apoptosis. Synergistic induction of apoptosis was also observed in other human leukemia cell types (eg, Jurkat, NB4). Coexposure of human leukemia cells to 17-AAG and the PKC inhibitor bisindolylmaleimide (GFX) did not result in enhanced lethality, arguing against the possibility that the PKC inhibitory actions of UCN-01 are responsible for synergistic interactions. The enhanced cytotoxicity of this combination was associated with diminished Akt activation and marked down-regulation of Raf-1, MEK1/2, and mitogen-activated protein kinase (MAPK). Coadministration of 17-AAG and UCN-01 did not modify expression of Hsp90, Hsp27, phospho-JNK, or phospho-p38 MAPK, but was associated with further p34cdc2 dephosphorylation and diminished expression of Bcl-2, Mcl-1, and XIAP. In addition, inducible expression of both a constitutively active MEK1/2 or myristolated Akt construct, which overcame inhibition of ERK and Akt activation, respectively, significantly attenuated 17-AAG/UCN-01-mediated lethality. Together, these findings indicate that the Hsp90 antagonist 17-AAG potentiates UCN-01 cytotoxicity in a variety of human leukemia cell types and suggest that interference with both the Akt and Raf-1/MEK/MAP kinase cytoprotective signaling pathways contribute to this phenomenon.
 
Progression-free survival. (A) Achievement of VGPR after induction therapy versus no therapy; (B) achievement of VGPR after induction versus after high-dose therapy; (C) achievement of VGPR after induction in VAD and bortezomib-dexamethasone arms versus no induction; (D) ISS stages 2 and 3, bortezomib-dexamethasone induction versus VAD; (E) poor-risk cytogenetics, bortezomib-dexamethasone induction versus VAD; (F) achievement of VGPR after induction in ISS stages 2 and 3 versus no induction; (G) achievement of VGPR after induction in poor-risk cytogenetics versus no induction. (A) P Ͻ .0001; (B) P ϭ .01; (C) P Ͻ .0001; (D) P ϭ .006; (E) P ϭ .11; (F) P Ͻ .0001; (G) P ϭ .0036. 
Analysis of factors associated with PFS in the intent-to-treat population (N 482)
Article
In the 2005-01 trial, we have demonstrated that bortezomib-dexamethasone as induction therapy before autologous stem cell transplantation was superior to vincristine-adriamycin-dexamethasone. We conducted a post-hoc analysis to assess the prognostic impact of initial characteristics as well as response to therapy in patients enrolled in this study. Multivariate analysis showed that ISS stages 2 and 3 and achievement of response less than very good partial response (VGPR) both after induction therapy and after autologous stem cell transplantation were adverse prognostic factors for progression-free survival, the most important one being achievement of response less than VGPR after induction. Progression-free survival was significantly improved with bortezomib-dexamethasone induction therapy in patients with poor-risk cytogenetics and ISS stages 2 and 3 compared with vincristine-adriamycin-dexamethasone. In these 2 groups of patients, achievement of at least VGPR after induction was of major importance. This study is registered with EudraCT (https://eudract.ema.europa.eu; EUDRACT 2005-000537-38) and http://clinicaltrials.gov (NCT00200681).
 
Article
AHA is caused by autoantibodies against factor VIII (FVIII). Immunosuppressive treatment (IST) results in remission of disease in 60-80% of patients over a period of days to months. IST is associated with frequent adverse events, including infections as a leading cause of death. Predictors of time to remission could help guiding IST intensity, but have not been established. We analyzed prognostic factors in 102 prospectively enrolled patients treated with a uniform IST protocol. Partial remission (PR, defined as no active bleeding, FVIII restored >50 IU/dl, hemostatic treatment stopped >24 h) was achieved by 83% of patients after a median of 31 days (range 7-362). Patients with baseline FVIII <1 IU/dl achieved PR less often and later (77%, 43 days) than patients with ≥1 IU/dl (89%, 24 days). After adjustment for other baseline characteristics, low FVIII remained associated with a lower rate of PR (hazard ratio 0.52, 95% confidence interval 0.33-0.81, p<0.01). In contrast, PR achieved on steroids alone within ≤21 days was more common in patients with FVIII ≥1 IU/dl and inhibitor concentration <20 BU/ml (odds ratio 11.2, p<0.0001). Low FVIII was also associated with a lower rate of complete remission and decreased survival. In conclusion, presenting FVIII and inhibitor concentration are potentially useful to tailor IST in AHA. Copyright © 2014 American Society of Hematology.
 
Article
The effects of combined exposure to the checkpoint abrogator UCN-01 and pharmacologic MEK1/2 inhibitors were examined in human multiple myeloma (MM) cell lines. Treatment of RPMI8226, NCI-H929, and U266 MM cells with a minimally toxic concentration of UCN-01 (150 nM) for 24 hours resulted in mitogen-activated protein (MAP) kinase activation, an effect that was blocked by coadministration of the MEK1/2 inhibitor PD184352. These events were accompanied by enhanced activation of p34(cdc2) and a marked increase in mitochondrial damage (loss of DeltaPsim; cytochrome c and Smac/DIABLO (direct IAP binding protein with low pI) release), poly(ADP-ribose) polymerase (PARP) cleavage, and apoptosis. PD184352/UCN-01 also dramatically reduced clonogenic survival in each of the MM cell lines. In contrast to As(2)0(3), apoptosis induced by PD184352/UCN-01 was not blocked by the free-radical scavenger N-acetyl-L-cysteine. Whereas exogenous interleukin 6 substantially prevented dexamethasone-induced lethality in MM cells, it was unable to protect them from PD184352/UCN-01-induced apoptosis despite enhancing Akt activation. Insulinlike growth factor 1 (IGF-1) also failed to diminish apoptosis induced by this drug regimen. MM cell lines selected for a high degree of resistance to doxorubicin, melphalan, or dexamethasone, or displaying resistance secondary to fibronectin-mediated adherence, remained fully sensitive to PD184352/UCN-01-induced cell death. Finally, primary CD138(+) MM cells were also susceptible to UCN-01/MEK inhibitor-mediated apoptosis. Together, these findings suggest that simultaneous disruption of cell cycle and MEK/MAP kinase signaling pathways provides a potent stimulus for mitochondrial damage and apoptosis in MM cells, and also indicate that this strategy bypasses the block to cell death conferred by several other well-described resistance mechanisms.
 
S-phase arrest by ara-C: Abrogation by UCN-01. Exponentially growing ML-1 cells were incubated with 50 nM ara-C for 24 hr (), at which time the culture was split and UCN-01  
S-phase arrest by ara-C: Abrogation by UCN-01. Exponentially growing ML-1 cells
Clonogenic assays. (A) Effect of ara-C (,) and ara-C in combination with UCN-01 (,) on the clonogenic survival of CFU-GM progenitor cells from normal bone marrow (B) Effect of ara-C (,,,) alone, UCN-01 alone (,,,‫)׀‬ and ara-C in combination with UCN-01 (,,,) on the clonogenic survival of AML blasts. Symbols indicate individual patients.  
Response of the checkpoint, survival and stress activated kinases within a cell sample from Patient 4. Effect of ara-C and UCN-01 on levels of pSer 345 Chk1, total Chk1, pTyr 15 Cdk2, total Cdk2, pSer 473 Akt, total Akt and JNK activation from AML blasts of Patient 4 during therapy.  
Effect of ara-C alone and in combination with UCN-01 on survival pathways and stress activated kinases. (A) pSer 473 Akt relative to total Akt levels in 8 individuals during therapy. (B) Change in JNK activity in 8 individuals during therapy measured as described in  
Article
Chk1 and Akt signaling facilitate survival of cells treated with nucleoside analogues. Activation of Chk1 in response to cytarabine (ara-C) induced an S-phase checkpoint characterized by the inhibition of Cdk2, cell cycle arrest, no change in constitutively active Akt, or low-stress kinase signaling in ML-1 cells. However, inhibition of Chk1 by UCN-01 in S-phase-arrested cells resulted in an abrogation of the checkpoint, inhibition of Akt, activation of JNK, and a rapid induction of apoptosis. Similarly, primary acute myelogenous leukemia (AML) blasts exposed to ara-C and UCN-01 demonstrated a selective loss in cloning potential when compared with normal progenitors. Therefore, we evaluated a pilot clinical trial of ara-C in combination with UCN-01 in patients with relapsed AML. Blasts from some patients demonstrated a previously activated Chk1-Cdk2 DNA damage response pathway that decreased during therapy. Constitutively phosphorylated Akt kinase declined on addition of UCN-01 to the ara-C infusion, an action accompanied by an activation of JNK and reduction in absolute AML blast counts. Thus, use of UCN-01 in combination with ara-C decreases Chk1 phosphorylation, inhibits the Akt survival pathway, and activates JNK during the course of therapy, offering a rationale for the cytotoxic action of this combination during AML treatment.
 
Article
Interactions between the Chk1 inhibitor UCN-01 and the farnesyltransferase inhibitor L744832 were examined in human leukemia cells. Combined exposure of U937 cells to subtoxic concentrations of UCN-01 and L744832 resulted in a dramatic increase in mitochondrial dysfunction, apoptosis, and loss of clonogenicity. Similar interactions were noted in other leukemia cells (HL-60, Raji, Jurkat) and primary acute myeloid leukemia (AML) blasts. Coadministration of L744832 blocked UCN-01-mediated phosphorylation of mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (MEK/ERK), leading to down-regulation of phospho-cyclic adenosine monophosphate responsive element-binding protein (phospho-CREB) and -p90(RSK) and activation of p34(cdc2) and stress-activated protein kinase/ERK kinase/c-Jun N-terminal kinase (SEK/JNK). Combined treatment also resulted in pronounced reductions in levels of phospho-Akt, -glycogen synthase kinase-3 (-GSK-3), -p70(S6K), -mammalian target of rapamycin (-mTOR), -forkhead transcription factor (-FKHR), -caspase-9, and -Bad. Ectopic expression of Bcl-2 or Bcl-xL but not dominant-negative caspase-8 blocked UCN-01/L744832-mediated mitochondrial dysfunction and apoptosis but did not prevent activation of p34(cdc2) and JNK or inactivation of MEK/ERK and Akt. Enforced expression of myristoylated Akt but not constitutively active MEK significantly attenuated UCN-01/L744832-induced apoptosis. However, dual transfection with Akt and MEK resulted in further protection from UCN-01/L744832-mediated lethality. Finally, down-regulation of JNK1 by siRNA significantly reduced the lethality of the UCN-01/L744832 regimen. Together, these findings suggest that farnesyltransferase inhibitors interrupt the cytoprotective Akt and MAPK pathways while reciprocally activating SAPK/JNK in leukemia cells exposed to UCN-01 and, in so doing, dramatically increase mitochondria-dependent apoptosis.
 
HLA-A haplotype frequencies
Genotype frequencies in patients with EBV HL and control participants
Article
Previous studies showed that the HLA class I region is associated with Epstein-Barr virus (EBV)-positive Hodgkin lymphoma (HL) and that HLA-A is the most likely candidate gene in this region. This suggests that antigenic presentation of EBV-derived peptides in the context of HLA-A is involved in the pathogenesis of EBV+ HL by precluding efficient immune responses. We genotyped exons 2 and 3, encoding the peptide-binding groove of HLA-A, for 32 single nucleotide polymorphisms in 70 patients with EBV+ HL, 31 patients with EBV- HL, and 59 control participants. HLA-A*01 was significantly overrepresented and HLA-A*02 was significantly underrepresented in patients with EBV+ HL versus controls and patients with EBV- HL. In addition, HLA-A*02 status was determined by immunohistochemistry or HLA-A*02-specific polymerase chain reaction (PCR) on 152 patients with EBV+ HL and 322 patients with EBV- HL. The percentage of HLA-A*02+ patients in the EBV+ HL group (35.5%) was significantly lower than in 6107 general control participants (53.0%) and the EBV- HL group (50.9%). Our results indicate that individuals carrying the HLA-A*02 allele have a reduced risk of developing EBV+ HL, while individuals carrying the HLA-A*01 allele have an increased risk. It is known that HLA-A*02 can present EBV-derived peptides and can evoke an effective immune response, which may explain the protective phenotype.
 
Article
Interactions between UCN-01 and HMG-CoA reductase inhibitors (ie, statins) have been examined in human leukemia and myeloma cells. Exposure of U937 and U266 cells to minimally toxic concentrations of UCN-01 and various statins (eg, lovastatin, simvastatin, or fluvastatin) dramatically increased mitochondrial dysfunction, caspase activation, and apoptosis. Comparable effects were observed in other leukemia and myeloma cell lines as well as in primary acute myeloid leukemia (AML) blasts but not in normal hematopoietic cells. Potentiation of UCN-01 lethality by lovastatin was associated with disruption of Ras prenylation and activation. These events were significantly attenuated by farnesyl pyrophosphate (FPP) but not by geranylgeranyl pyrophosphate (GGPP), implicating perturbations in farnesylation rather than geranylgeranylation in synergistic interactions. Coexposure to statins and UCN-01 resulted in inactivation of ERK1/2 and Akt, accompanied by JNK activation. U266 cells ectopically expressing JNK1-APF, a dominant negative JNK1 mutant, displayed significantly reduced susceptibility to lovastatin/UCN-01-mediated lethality. Moreover, transfection of U266 cells with constitutively activated H-Ras (Q61L) attenuated ERK1/2 inactivation and dramatically diminished the lethality of this regimen. Collectively, these findings indicate that HMG-CoA reductase inhibitors act through a Ras farnesylation-associated mechanism to induce signaling perturbations, particularly prevention of Ras and ERK1/2 activation, in UCN-01-treated cells, resulting in the synergistic induction of cell death.
 
Article
A human megakaryoblastic cell line (MEG-01) was investigated for the presence of protein S in culture medium and cell lysates using a specific enzyme-linked immunoassay (ELISA) and a functional assay. When 5 X 10(5) MEG-01 cells/mL was subcultured in RPMI 1640 medium with 10% fetal calf serum (FCS), the concentration of protein S antigen in the culture medium increased progressively with time from less than 8 ng/mL on day 0 to 105.6 +/- 6.0 ng/mL on day 13. Vitamin K2(1 microgram/mL) increased the production of functional protein S, whereas warfarin (1 microgram/mL) profoundly decreased the quantity and the specific activity of secreted protein S. By an indirect immunofluorescent technique, protein S antigen was detected in both MEG-01 cells and human bone marrow megakaryocytes. Immunoblot analysis of culture medium revealed two distinct bands (mol wt 84,000 and 78,000) that are identical to the doublets of purified plasma protein S. De novo synthesis of protein S was demonstrated by the presence of specific immunoprecipitable radioactivity in the medium after 5 hours of labeling of the cells with [35S]-methionine as a 84,000 mol wt protein. Plasma protein S levels of nine patients with severe aplastic anemia were not significantly different from those of normal controls. These results suggest that megakaryocytes produce functional protein S and contain the enzymes required for the carboxylation of selected glutamic acid residues, and that protein S synthesized by megakaryocytes does not represent a main source of plasma protein S.
 
Article
Interactions between pharmacologic NF-kappaB inhibitors (eg, Bay 11-7082, SN-50) and the checkpoint abrogator UCN-01 have been examined in human multiple myeloma (MM) cells. Exposure of U266 cells to Bay 11-7082 (Bay) in combination with UCN-01 resulted in the abrogation of NF-kappaB/DNA binding activity and the synergistic induction of apoptosis. Comparable synergism was observed in other MM cell lines and patient-derived CD138+ cells and between an inhibitory peptide of NF-kappaB (SN50) and UCN-01. Bay/UCN-01-mediated lethality involved mitochondrial dysfunction, caspase cleavage, and poly adenosine diphosphate-ribose polymerase (PARP) degradation. Although Bay modestly blocked UCN-01-induced extracellular signal-regulated kinase (ERK) phosphorylation, coadministration activated c-Jun N-terminal kinase (JNK) and cdc2/cdk1 and down-regulated Mcl-1, XIAP, and Bcl-xL. Transfection with a constitutively activated mitogen-activated protein kinase kinase (MEK1)/green fluorescent protein (GFP) construct failed to block apoptosis induced by Bay/UCN-01 but significantly attenuated MEK inhibitor (U0126)/UCN-01-induced lethality. Inhibiting JNK activation with SP600125 or D-JNKI1 peptide markedly reduced Bay/UCN-01-mediated mitochondrial dysfunction and apoptosis and the down-regulation of Mcl-1, XIAP, and Bcl-xL but not of cdc2/cdk1 activation. Stable transfection of cells with dominant-negative caspase-9 dramatically diminished Bay/UCN-01 lethality without altering JNK or cdc2/cdk1 activation. Neither interleukin-6 (IL-6)- nor fibronectin-mediated adherence conferred resistance to Bay/UCN-01-induced apoptosis. Together, these findings suggest that a strategy combining UCN-01 with disruption of the IkappaB kinase (IKK)/IkappaB/NF-kappaB pathway warrants attention in MM.
 
EFS for all children treated on 4 consecutive DFCI ALL Consortium protocols. Consortium protocols shown are: 81-01 (1981-1985), 85-01 (1985-1987), 87-01 (1987-1991), and 91-01 (1991-1995). There was significant difference (P ϭ .03) in EFS when comparing all 4 protocols, with most favorable results observed on Protocol 91-01 (5-year EFS Ϯ SE, 83% Ϯ 2%). 
Therapy on DFCI ALL Consortium Protocol 91-01
Results of Protocol 91-01 for 377 children with ALL
Outcome by randomizations
Article
The Dana-Farber Cancer Institute (DFCI) acute lymphoblastic leukemia (ALL) Consortium Protocol 91-01 was designed to improve the outcome of children with newly diagnosed ALL while minimizing toxicity. Compared with prior protocols, post-remission therapy was intensified by substituting dexamethasone for prednisone and prolonging the asparaginase intensification from 20 to 30 weeks. Between 1991 and 1995, 377 patients (age, 0-18 years) were enrolled; 137 patients were considered standard risk (SR), and 240 patients were high risk (HR). Following a 5.0-year median follow-up, the estimated 5-year event-free survival (EFS) +/- SE for all patients was 83% +/- 2%, which is superior to prior DFCI ALL Consortium protocols conducted between 1981 and 1991 (P =.03). There was no significant difference in 5-year EFS based upon risk group (87% +/- 3% for SR and 81% +/- 3% for HR, P =.24). Age at diagnosis was a statistically significant prognostic factor (P =.03), with inferior outcomes observed in infants and children 9 years or older. Patients who tolerated 25 or fewer weeks of asparaginase had a significantly worse outcome than those who received at least 26 weeks of asparaginase (P <.01, both univariate and multivariate). Older children (at least 9 years of age) were significantly more likely to have tolerated 25 or fewer weeks of asparaginase (P <.01). Treatment on Protocol 91-01 significantly improved the outcome of children with ALL, perhaps due to the prolonged asparaginase intensification and/or the use of dexamethasone. The inferior outcome of older children may be due, in part, to increased intolerance of intensive therapy.
 
Article
To the editor: Expression of the common class I human leukocyte antigen (HLA) A*01 has recently been shown to increase the risk of developing Epstein-Barr virus (EBV)–positive Hodgkin lymphoma (HL).[1][1] Furthermore, genetic markers closely linked to the HLA-A*01 allele were also shown to be
 
Article
In a retrospective analysis, we previously reported that children whose leukemia cells harbored the TEL/AML1 gene rearrangement have excellent outcomes. From 1996 to 2000, we conducted a prospective study to determine the incidence and outcomes of children with TEL/AML1-positive acute lymphoblastic leukemia (ALL). Children with newly diagnosed ALL were treated on DFCI ALL Consortium Protocol 95-01. Patients were risk stratified primarily by current National Cancer Institute (NCI)-Rome risk criteria. With a median follow-up of 5.2 years, the 5-year event-free survival for TEL/AML1-positive patients was 89% compared with 80% for TEL/AML1-negative B-precursor patients (P = .05). The 5-year overall survival rate was 97% among TEL/AML-positive patients compared with 89% among TEL/AML1-negative patients (P = .03). However, in a multivariable analysis, risk group (age and leukocyte count at diagnosis) and asparaginase treatment group, but not TEL/AML1 status, were found to be independent predictors of outcome. We conclude that TEL/AML1-positive patients have excellent outcomes, confirming our previous findings. However, factors such as age at diagnosis and presenting leukocyte count should be taken into consideration when treating this group of patients.
 
Article
We evaluated event-free survival (EFS) and leukemia-free interval (LFI) of children treated for acute lymphoblastic leukemia (ALL). Patients were randomized to receive either a low dose or high dose of methotrexate (MTX) as a single agent at the time of diagnosis. Five days later, multidrug therapy was begun. We assessed the early antileukemic efficacy of the two doses of MTX, as well as toxicity and long-term efficacy. An increase in cell kill, as indicated by a larger decrease in the percentage of viable cells in the bone marrow between days 0 and 5, was observed for the high-dose MTX group when compared with the low-dose MTX group (P = .04). At 7.1 years of median follow-up, the 38 children randomized to receive high-dose MTX had a better EFS and LFI compared with the 39 patients randomized to receive low-dose MTX. The 7-year percentages (+/- SE) for EFS were 82% +/- 6% for high-dose MTX and 69% +/- 7% for low-dose MTX (P = .13). The 7-year percentages for LFI were 91% +/- 5% and 69% +/- 7%, respectively (P = .01). We recommend that high-dose MTX be considered as an effective addition to induction therapy in childhood ALL.
 
Article
The role of Bim in synergistic interactions between UCN-01 and MEK1/2 inhibitors in human multiple myeloma cells was investigated. Exposure of U266 or RPMI8226 cells to UCN-01 resulted in ERK1/2 activation-associated Bim(EL) phosphorylation/down-regulation, events abrogated by MEK1/2 inhibitors. Enforced activation of ERK1/2 by transfection with constitutively active MEK1 diminished the capacity of PD98059 but not PD184352 to block UCN-01-mediated Bim(EL) phosphorylation and to potentiate apoptosis. Cotreatment with MEK1/2 inhibitors increased the association of Bim(EL) with both Bcl-2 and Bcl-x(L) in UCN-01-treated cells, leading to Bax/Bak conformational change and Bax mitochondrial translocation. Down-regulation of Bim(EL) by shRNA substantially diminished UCN-01/MEK inhibitor-mediated Bax/Bak activation and apoptosis. Furthermore, transfection of cells with S65A Bim, a mutant resistant to UCN-01-mediated phosphorylation, significantly sensitized cells to UCN-01 lethality. Conversely, ectopic expression of either Bcl-2 or Bcl-x(L) did not alter UCN-01/MEK1/2 inhibitor-mediated modifications in Bim(EL) phosphorylation but largely prevented cell death. Finally, IL-6 or IGF-1 failed to prevent MEK1/2 inhibitors from blocking UCN-01-induced Bim(EL) phosphorylation/degradation or cell death. Collectively, these findings argue that UCN-01-mediated ERK1/2 activation leads to Bim(EL) phosphorylation/inactivation, resulting in cytoprotection, and that interference with these events by MEK1/2 inhibitors plays a critical role in synergistic induction of apoptosis by these agents.
 
A 
Outcome of Asparaginase Randomization 
Article
The Dana-Farber Cancer Institute (DFCI) Childhood ALL Consortium Protocol 95-01 was designed to minimize therapy-related morbidity for children with newly diagnosed ALL without compromising efficacy. Patients participated in randomized comparisons of (1) doxorubicin given with or without dexrazoxane, a cardioprotectant (high-risk patients), (2) intensive intrathecal chemotherapy and cranial radiation (standard-risk patients), and (3) Erwinia and Escherichia coli asparaginase (all patients). Between 1996 and 2000, 491 patients (aged 0-18 years) were enrolled (272 standard risk and 219 high risk). With a median of 5.7 years of follow-up, the estimated 5-year event-free survival (EFS) for all patients was 82%+/-2%. Dexrazoxane did not have a significant impact on the 5-year EFS of high-risk patients (P=.99), and there was no significant difference in outcome of standard-risk patients based on type of central nervous system (CNS) treatment (P=.26). Compared with E coli asparaginase, Erwinia asparaginase was associated with a lower incidence of toxicity (10% versus 24%), but also an inferior 5-year EFS (78%+/-4% versus 89%+/-3%, P=.01). We conclude that (1) dexrazoxane does not interfere with the antileukemic effect of doxorubicin, (2) intensive intrathecal chemotherapy is as effective as cranial radiation in preventing CNS relapse in standard-risk patients, and (3) once-weekly Erwinia is less toxic than E coli asparaginase, but also less efficacious.
 
Article
We evaluated the outcome of 482 children with acute myeloid leukemia (AML) enrolled in the Associazione Italiana di Ematologia e Oncologia Pediatrica AML 2002/01 trial. Treatment was stratified according to risk group; hematopoietic stem cell transplantation (HSCT) was used in high-risk (HR) children. Patients with core binding factor leukemia achieving complete remission (CR) after the first induction course were considered standard risk (SR; 99 patients), whereas the others (n = 383) were assigned to the HR group. Allogeneic (ALLO) or autologous (AUTO) HSCT was employed, respectively, in 141 and 102 HR patients after consolidation therapy. CR, early death, and induction failure rates were 87%, 3%, and 10%, respectively. Relapse occurred in 24% of patients achieving CR. The 8-year overall survival (OS), event-free survival (EFS), and disease-free survival (DFS) were 68%, 55%, and 63%, respectively. OS, EFS, and DFS for SR and HR patients were 83%, 63%, and 66% and 64%, 53%, and 62%. DFS was 63% and 73% for HR patients given AUTO-HSCT and ALLO-HSCT, respectively. In multivariate analysis, risk group, white blood cell >100 × 10(9)/L at diagnosis, and monosomal karyotype predicted poorer EFS. Risk-oriented treatment and broad use of HSCT result in a long-term EFS comparing favorably with previously published studies on childhood AML.
 
Estimates from the final Cox model of FFR with high versus low MRD at end of induction, risk group, and treatment group included as covariates 
Article
In a prospective trial in 284 children with B-lineage acute lymphoblastic leukemia (ALL), we assessed the clinical utility of real-time quantitative polymerase chain reaction analysis of antigen receptor gene rearrangements for detection of minimal residual disease (MRD) to identify children at high risk of relapse. At the end of induction therapy, the 5-year risk of relapse was 5% in 176 children with no detectable MRD and 44% in 108 children with detectable MRD (P < .001), with a linear association of the level of MRD and subsequent relapse. Recursive partitioning and clinical characteristics identified that the optimal cutoff level of MRD to predict outcome was 10(-3). The 5-year risk of relapse was 12% for children with MRD less than one leukemia cell per 10(3) normal cells (low MRD) but 72% for children with MRD levels greater than this level (high MRD) (P < .001) and children with high MRD had a 10.5-fold greater risk of relapse. Based upon these results we have altered our treatment regimen for children with B-lineage ALL and children with MRD levels greater than or equal to 10(-3) at the end of 4 weeks of multiagent induction chemotherapy now receive intensified treatment to attempt to decrease their risk of subsequent relapse.
 
Article
The addition of rituximab to cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy results in significant improvement in clinical outcome for individuals with non-HIV-associated aggressive B-cell lymphoma. To assess the potential risks and benefits of the addition of rituximab to CHOP for HIV-associated non-Hodgkin lymphoma (HIV-NHL) 150 patients receiving CHOP for HIV-NHL were randomized (2:1) to receive 375 mg/m(2) rituximab with each chemotherapy cycle (n = 99) or no immunotherapy (n = 50) in a multicenter phase 3 trial. The complete response rate (CR + CRu) was 57.6% for R-CHOP and 47% for CHOP (P = .147). With a median follow-up of 137 weeks, time to progression, progression-free survival, and overall survival times were 125, 45, and 139 weeks, respectively, for R-CHOP and 85, 38, and 110 weeks, respectively, for CHOP (P = not significant, all comparisons). Treatment-related infectious deaths occurred in 14% of patients receiving R-CHOP compared with 2% in the chemotherapy-alone group (P = .035). Of these deaths, 60% occurred in patients with CD4 counts less than 50/mm(3). Progression-free survival was significantly influenced by CD4(+) count (P < .001) and International Prognostic Index score (P = .022), but not bcl-2 status. The addition of rituximab to CHOP in patients with HIV-NHL may be associated with improved tumor responses. However, these benefits may be offset by an increase in infectious deaths, particularly in those individuals with CD4(+) lymphocyte counts less than 50/mm(3).
 
Article
In neonatal alloimmune thrombocytopenia, almost all human platelet antigen (HPA)-1b1b mothers who produce anti-HPA-1a antibody through carrying an HPA-1a fetus are human histocompatibility leukocyte antigen (HLA)-DRB3*0101 positive. It is predicted that the HPA-1a Leu(33) polymorphism forms part of an HLA-DRB3*0101-restricted T-helper epitope, and acts as an anchor residue for binding this class II molecule. However, it is not known whether any corresponding peptides are naturally processed and presented from platelet glycoprotein. In this study, peptides displayed by a homozygous HLA-DRB3*0101 antigen-presenting cell line were identified after pulsing with recombinant HPA-1a (Leu(33) plexin-semaphorin-integrin domain). The peptides were eluted from HLA-DR molecules, fractionated by high performance liquid chromatography, and analyzed by tandem mass spectrometry. A "nested set" of naturally presented HPA-1a-derived peptides, each containing the Trp(25)-Leu(33) core epitope, was identified, with the most abundant member being the 16-mer Met(22)-Arg(37). These peptides may provide the basis for novel treatments to tolerize the corresponding T-helper response in women at risk of neonatal alloimmune thrombocytopenia.
 
Identification and isolation of CD4 T cells that proliferated specifically in response to the L33 peptide. PBMCs drawn from an HPA-1a– alloimmunized woman were stimulated in vitro with L33 peptide for weeks in tissue culture, then labeled with CFSE dye, and stimulated again with L33 peptide or Lol P1 control peptide in parallel cultures. After 13 days, the cultures were assayed for proliferation by flow cytometry. A sort gate was set to define an area for optimal enrichment of HPA-1a–specific proliferating CD4 T cells by FACS. CD3 CD4 lymphocytes that underwent enhanced proliferation in response to L33 peptide (1.4%; left) represented a considerably enriched population compared with the control culture (0.3%; right). The displays are biexponential (see " Cell culture and generation of HPA-1a–specific T-cell lines " ). 
Confirmation of peptide-specificity of isolated CD4 T-cell clones. Clonal CD4 T cells were cocultured for 36 hours with 50 000 peptide-pulsed B lymphoblasts and assayed for IFN secretion with the ELISPOT assay technique. HPA-1a–derived peptide L33, but not peptide Lol P1, induced IFN secretion. Duplicate assays are shown. Two hundred T cells were assayed per well of clones D7T1 and D7T4, and the number of D7T5, D7T8, and D7T9 was not determined. Wells marked " APC only " contained peptide-pulsed B lymphoblasts and no T cells. APC indicates antigen-presenting cell. 
Clonal T-cell lines D7T1 and D7T4 have different T-cell receptors TCRB rearrangements CDR3
MHC restriction of L33-specific T-cell clones. MHC restriction was determined by ELISPOT: L33-specific T-cell clones were assayed for IFN secretion in response to stimulation with a panel of matched, MHC class II homozygous APCs. Only STEINLIN cells pulsed with peptide L33, but not Lol P1 or P33 peptides, induced IFN secretion. On the basis of the combined MHC class II expression pattern of the 3 APCs, it could be deduced that L33 peptide recognition by the T-cell clones is restricted by HLA-DRB3*0101. Similar results were obtained with both D7T1 and D7T4 T-cell clones. Duplicate assays with D7T4 cells are shown. The MHC alleles expressed by the 3 APCs are shown in Table 3. 
L33-specific T-cell clones respond specifically to HLA-DRB3*0101–positive monocytes pulsed with either synthetic peptide or HPA-1a–positive platelets. Proliferative responses induced by stimulation with peptide-pulsed or platelet-pulsed monocytes. Both clones proliferate specifically in response to (A) L33, but not Lol P1 and P33 control, peptides, and (B) HPA-1a–positive, but not HPA-1a–negative, platelets. (C) D7T1 and D7T4 T-cell clones proliferate in response to stimulation with HPA-1a–positive platelets (HPA-1aa or HPA-1ab), but not HPA-1a–negative (HPA-1bb) platelets, combined with HLA-DRB3*0101–positive, but not negative, monocytes. Representative data for clone D7T4 is shown. 
Article
T-cell responses have been implicated in the development of HPA-1a-induced neonatal alloimmune thrombocytopenia (NAIT). However, HPA-1a-specific T cells have neither been isolated nor characterized. Here, we aimed to determine whether HPA-1a-specific T cells could be isolated from HPA-1a-immunized women. In the present study, peripheral blood mononuclear cells (PBMCs) from an HPA-1a-alloimmunized woman were cultured for weeks in the presence of HPA-1a peptide, labeled with CFSE, and assayed for antigen-specific proliferation. Individual proliferating cells were isolated by fluorescence-activated cell sorting and expanded in culture. Antigen specificity and HLA restriction were determined by cytokine secretion (enzyme-linked immunospot [ELISPOT]) and proliferation assays. Several CD3(+)CD4(+) T-cell clones were isolated that proliferated and secreted cytokines in response to HPA-1a peptide. Two of these clones have been established in long-term culture in our laboratory. Both of these recognize synthetic as well as naturally processed HPA-1a antigen, and the recognition is restricted by the MHC molecule HLA-DRB3*0101 that is strongly associated with NAIT. These HPA-1a-specific T-cell clones represent unambiguous evidence for the association of T-cell responses with NAIT, and they will serve as unique tools to elucidate the cellular immune response that may result in NAIT.
 
Paired analysis of PML-RAR ␣ NQs from 140 simultaneously obtained, evaluable BM and PB samples from INT0129 patients. Values obtained by dividing PML-RAR ␣ copy number by GAPDH copy number for BM (abscissa) and PB (ordinate) are co-plotted on a log 10 scale marked by negative exponents. Values 
Distribution of evaluable low- and high-sensitivity range samples and of PML-RAR ␣ ؉ samples at 4 INT0129 monitoring-interval checkpoints. The 
Clinical course and serial monitoring of PML-RAR ␣ NQs derived from bone marrow and/or peripheral blood by real-time quantitative RT-PCR in 2 patients treated on protocol INT0129. (A) Patient 1 received induction treatment with daunorubicin plus cytarabine (DA) and, after 2 courses of DA consolidation chemotherapy, received all- trans retinoic acid (ATRA) maintenance therapy for 1 year. (B) Patient 2 received remission induction treatment with ATRA and, after 2 courses of DA consolidation chemotherapy, received no further treatment. Both patients are in continuing clinical remission after longer than 5 years follow-up. The monitoring intervals designated on the abscissa are representational and not time-linear. PML-RAR ␣ NQs, indicated on the left ordinate, were determined by dividing PML-RAR ␣ copy number by GAPDH copy number. Bone marrow NQs, stippled columns; peripheral blood NQs, hatched columns. Assay sensitivity is represented by the reciprocal of the GAPDH copy number (1 divided by the GAPDH copy number), indicated on the right ordinate. The sensitivity cutoff at 1/2.5 ϫ 10 5 
Article
The potential prognostic value of quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR [qrtPCR]) measurements of PML-RAR alpha mRNA in acute promyelocytic leukemia was retrospectively assessed before treatment and at 3 posttreatment intervals in 123 patients on intergroup protocol 0129. The primary measure was the PML-RAR alpha(GAPDH) normalized quotient (NQ), that is, PML-RAR alpha mRNA copies divided by glyceraldehyde-3'-phosphate dehydrogenase (GAPDH) mRNA copies. Only samples with more than 2.5 x 10(5) copies of the housekeeping gene GAPDH mRNA (detection sensitivity exceeding 10(4)) were considered NQ evaluable. With RNA from low-density selected cells, paired peripheral blood (PB) and bone marrow samples (n = 140) had comparable NQs (P <.001). Before treatment, high NQ was associated with short-form PML-RAR alpha (P <.001), but not with white blood cell count or clinical outcome. Following treatment, NQ was lower in all-trans retinoic acid-induced complete remission (CR) than chemotherapy-induced CR (P =.018) and at first test after consolidation chemotherapy (P =.037). After consolidation chemotherapy, patients with NQ exceeding 10(-5) had 4.1-fold increased relapse risk (P =.008); however, 73% of patients who experienced relapse had NQ lower than 10(-5). In the follow-up period (FUP), any NQ exceeding 10(-5) and 10(-6) had 17.5-fold and 7.6-fold increased relapse risk, respectively (P <.001), while no gradation of relapse risk (approximately 18%) could be identified at NQ lower than 10(-6), including NQ(-). These results indicate that qrtPCR monitoring of PML-RAR alpha NQ can identify patients at high risk of relapse and suggest that clinically practical PB NQ monitoring at more frequent FUP intervals may improve predictive accuracy for relapse or continuing CR in patients with persistent, fluctuating minimal residual disease levels.
 
Article
The type V (for variable) promyelocytic leukemia retinoic acid receptor (PML-RAR)alpha transcript, found in approximately 8% of adult patients with acute promyelocytic leukemia (APL), is defined molecularly by truncation of PML exon 6 and frequent insertion of genetic material from RARalpha intron 2. To more fully characterize the molecular features of PML-RARalpha V-type transcripts and to determine whether V-form APL patients have a distinct clinical presentation or prognosis, we analyzed 18 adult V-form APL patients enrolled on Intergroup protocol 0129 (INT-0129). Truncations in PML exon 6 ranged from 8 to 146 nucleotides, and 3 to 127 extra nucleotides (1 to 42 extra amino acids) were inserted at the PML exon 6/RARalpha exon 3 junction in 13 cases. No distinguishing morphologic, cytogenetic, or immunophenotypic features of V-form blasts were identified. A total of 5 of 7 patients induced with ATRA and 8 of 11 patients who received chemotherapy for induction achieved complete remission (CR). Six patients have relapsed, 4 after chemotherapy induction and 2 after ATRA. Nine patients (50%) are alive, 6 in continuous CR, 2 after salvage therapy for relapsed or refractory disease, and 1 after alternative treatment following early removal from protocol. Although the failure rate for V-form APL patients was high (61%), the low power of the current study to detect clinically significant differences precludes a meaningful comparison of clinical outcomes between the 18 V-form cases and non-V-form adult APL patients enrolled on INT-0129. (Blood. 2000;95:398-403)
 
Dose and schedule
Demographics and baseline characteristics
Adverse events occurring in >5% of patients (n 5 83)
Article
Otlertuzumab is a novel humanized anti-CD37 protein therapeutic. This study evaluated the safety of otlertuzumab administered intravenously to patients with chronic lymphocytic leukemia (CLL). Otlertuzumab was administered weekly for up to 8 weeks followed by 1 dose per month for 4 months ranging from 0.03 to 20 mg/kg in the dose-escalation phase and 10 to 30 mg/kg in the dose-expansion phase. Responses were determined by using the 1996 National Cancer Institute (NCI-96) and 2008 International Workshop on Chronic Lymphocytic Leukaemia (IWCLL) criteria. Fifty-seven patients were treated in the dose-escalation phase and 26 in the dose-expansion phase. A maximum-tolerated dose was not identified. Response occurred in 19 (23%) of 83 treated patients by NCI-96 criteria. All responses were partial and occurred more commonly in patients with symptomatic untreated CLL (6/7) or 1 to 2 prior therapies (12/28) vs 3 or more therapies (1/48). Twenty percent (12/61) with serial computed tomography scan assessment had a response per IWCLL criteria. The most frequent adverse events were infusion reactions, fatigue, nausea, and diarrhea and were not dose related. Otlertuzumab was well tolerated, and modest clinical activity was observed. Otlertuzumab warrants further evaluation in combination with other agents for the treatment of CLL. This trial was registered at www.clinicaltrials.gov as #NCT00614042.
 
Classification of 23 selected studies according to their methodologic design
Sites of thrombosis
IRs of thrombosis for different groups of studies according to the overall population included
Article
Thrombotic complications in hematologic malignancies have important clinical implications. In this meta-analysis we sought to obtain accurate estimates of the thrombotic risk in lymphoma patients. Articles were searched in electronic databases and references. Eighteen articles were identified (29 cohorts, 18 018 patients and 1149 events). Pooled incidence rates (IRs) were calculated by the use of a method based on the exact maximum likelihood binomial distribution. The global IR of thrombosis was 6.4% (95% confidence interval [CI] 6.0%-6.8%). The global IRs of venous or arterial events were 5.3% (95% CI, 5.0%-5.7%) and 1.1% (95% CI, 0.9%-1.2%), respectively. The IR of thrombosis observed in subjects with non-Hodgkin lymphoma (NHL) was 6.5% (95% CI, 6.1%-6.9%), significantly greater than that observed for patients with Hodgkin lymphoma (4.7%; 95% CI, 3.9%-5.6%). Within NHL, patients with high-grade disease had a greater risk of events (IR 8.3%; 95% CI, 7.0%-9.9%) than low-grade disease (IR 6.3%; 95% CI, 4.5%-8.9%). This meta-analysis shows that the IR of thrombosis in lymphoma patients is quite high, especially in those with NHL at an advanced stage of the disease. These results may help better defining lymphoma populations at high thrombotic risk, to whom prophylactic approaches could be preferentially applied.
 
Article
The deoxyspergualin derivative LF 15-0195 has demonstrated some efficacy in animal models of autoimmune and graft-versus-host diseases and is currently tested in clinics. The molecular mechanisms of LF 15-0195 immunosuppressive activity remained unknown. We show that exposure to LF 15-0195 sensitizes Jurkat T cells to apoptosis induced by an agonistic anti-CD95 antibody (CH11 clone) and by the cytokine TNF-related apoptosis-inducing ligand. LF 15-0195 does not demonstrate any significant effect on the postmitochondrial activation of caspases, nor does it modify overall expression of CD95, Fas-associated death domain, and procaspase-8. The compound facilitates the recruitment of these molecules to the death-inducing signaling complex (DISC) and enhances caspase-8 and -10 activation, thus increasing cytochrome c and direct IAP binding with low pI (DIABLO)/Smac mitochondrial release. LF 15-0195 also sensitizes Jurkat T cells to CD3-mediated apoptosis, an in vitro model for activation-induced T-cell death (AICD). LF 15-0195-mediated sensitization to AICD was further confirmed in human peripheral T cells exposed to anti-CD3 antibodies, then cultured in the presence of interleukin-2. In these cells, LF 15-0195 increased apoptosis triggered by either anti-CD95 antibodies or CD3 restimulation, whereas no effect was observed on "passive apoptosis." Finally, in bone marrow recipient mice, LF 15-0195 enhanced allogeneic donor T-cell death, which required a functional CD95 pathway. These results suggest that LF 15-0195 sensitizes T cells to AICD by increasing caspase activation at the DISC level in response to CD95 engagement. This original mechanism, together with LF 15-0195 efficacy in various disease models, makes this compound a promising immunosuppressive drug.
 
Article
The effect of differentiation induction by a tumor-promoting phorbol diester, 12-O-tetradecanoylphorbol-13-acetate (TPA) on a clonal human megakaryoblastic cell line, MEG-O1s, was investigated, and a prominent response was demonstrated. The cells became weakly adherent, developed conspicuous cytoplasmic blebs, and displayed mature megakaryocytic characteristics by light microscopy such as the development of azurophilic cytoplasmic granules and a mosaic pattern of oxyphilic patches, multiplication of nuclei, and enhancement of the PAS reaction and alpha-naphthyl acetate esterase staining. Ultrastructural studies demonstrated the development of prominent cytoplasmic blebs, budding of blebs, and multiplication of nuclei. Numerous granules with central nucleoids that are similar to alpha granules had developed as well as granules with high electron density and clearly demarcated zones. Surface marker analysis revealed a moderate increase in IgG Fc receptor levels and a profound decrease in C3 receptor sites. By an immunofluorescent technique using monoclonal and polyclonal antibodies, a dramatic change in the expression of several megakaryocyte-platelet-specific proteins was demonstrated. All the proteins that had been expressed before induction such as platelet glycoprotein (GP) IIb/IIIa, fibrinogen, von Willebrand factor, factor XIIIA, beta-thromboglobulin (beta-TG), and HLA class 1 antigen were profoundly enhanced after induction by TPA. Induction by TPA led to the expression of fibronectin and factor V, which were not detected on nontreated cells. An ultrastructural immunoperoxidase study demonstrated platelet GPIb and GPIIb/IIIa in both plasma membranes and protein synthesis areas such as perinuclear cisternae and endoplasmic reticulum after TPA induction. beta-TG was also observed in some cytoplasmic granules of TPA-treated cells. TPA remarkably increased the secretion of beta-TG into the culture medium of MEG-01s. Ploidy was also increased from 2C to 4C to 4C to 8C. Similar maturation of MEG-01s was induced by other phorbol diester analogues such as phorbol-12,13-dibutyrate, but not by phorbol itself. These results indicate that phorbol diester, TPA, can bring about differentiation and maturation of a human megakaryoblastic cell line (MEG-01s) and that MEG-01s cells will provide a useful model for studying megakaryocytic differentiation and numerous megakaryocyte-platelet-specific proteins.
 
Article
MEG-01s, an established human megakaryoblastic leukemia cell line, exhibited specific high-affinity binding sites for [3H]iloprost, a stable prostaglandin (PG) I2 analogue, for [3H]SQ-29548, a stable thromboxane (TX) A2 antagonist and, for [3H]PGE2/PGE1, but not for [3H]PGD2. In the MEG-01s cells, iloprost/PGI2, or PGE1 stimulated cAMP production with ED50 values practically identical to the IC50 values for the [3H] iloprost binding. STA2 and U46619, TXA2/PGH2 agonists, PGE2/PGE1, iloprost/PGI2, and thrombin elevated the intracellular concentrations of Ca2+ ([Ca2+]i), as determined by Fura-2 fluorescence signals. Elevation of [Ca2+]i by PGE2/PGE1 and iloprost, but not that by TX-agonists or thrombin, was totally dependent on the presence of extracellular Ca2+. This effect by PGE2/PGE1 was partially inhibited by prior treatment of the cells with islet-activating protein (IAP), while that by TX-agonists or by PGI2/iloprost was not affected. We tentatively conclude from these results that: (1) MEG-01s cells express (a) PGI2/PGE1 receptor(s) coupled to adenylate cyclase and Ca2+ influx, a TXA2/PGH2 receptor coupled to the phosphatidylinositol-turnover-Ca2+ system, and the PGE2/PGE1 receptor coupled to Ca2+ influx; (2) the receptors for TXA2/PGH2 and iloprost and those for PGE2/PGE1 and thrombin are coupled to IAP-insensitive and IAP-sensitive GTP-binding proteins, respectively, and function in a different manner to elevate [Ca2+]i. Thus, the MEG-01s cell line is a pertinent model for studying eicosanoid receptor-mediated signal transduction in platelet/megakaryocyte systems.
 
IFM 2009-02 flow Diagram. 
(A-C) Survival end points per 21 of 28-day arm (N 5 43) and 28 of 28-day arm (N 5 41); Kaplan-Meier estimates (ITT). (A) Time to progression. (B) Progression-free survival. (C) Overall survival. (D-F) Survival end points in the entire population (N 5 84); Kaplan-Meier estimates (ITT). (D) Comparison between TTP on protocol and TTP on last prior line for all patients included in the study and for responders only (patients with either CR or VGPR or PR as per IMWG). (E) TTP In responders versus nonresponders as per IMWG criteria (eg, patients with stable disease including minimal response [SD]). (F) Overall survival in responders versus SD. O/N, number of events/number of patients in the group. 
Article
The combination of pomalidomide and dexamethasone can be safely administered to patients with multiple myeloma (MM) and has significant efficacy, although the optimal regimen remains to be determined. Patients with MM whose disease progressed after multiple lines of therapy have limited treatment options. We designed a multicenter, phase 2 randomized study assessing two different dose regimens of pomalidomide and dexamethasone in advanced MM. Treatment response was assessed centrally. Pomalidomide (4 mg) was given orally on days 1 to 21 (arm 21/28) or continuously (arm 28/28) over a 28-day cycle, plus dexamethasone given weekly. Eighty-four patients (43, arm 21/28 and 41, arm 28/28) were randomized. The median number of prior lines was 5. Overall response rate was 35% (arm 21/28) and 34% (arm 28/28), independent of the number of prior lines and level of refractoriness. Median duration of response, time to disease progression, and progression-free survival was 7.3, 5.4, and 4.6 months, respectively, which was similar across cohorts. At 23 months follow-up, median overall survival was 14.9 months, with 44% of the patients alive at 18 months. Toxicity consisted primarily of myelosuppression, which was manageable. The efficacy and safety data presented here, along with data from other phase 2 trials, suggest that pomalidomide 4 mg per day on days 1 to 21 of 28 with dexamethasone should be investigated in future trials. This trial is registered at ClinicalTrials.gov (No. NCT01053949).
 
Top-cited authors
Randy D Gascoyne
  • BC Cancer Agency
Martin S. Tallman
  • Memorial Sloan Kettering Cancer Center
Richard Larson
  • University of Chicago
Michael J Borowitz
  • Johns Hopkins Medicine
Elaine S Jaffe
  • National Institutes of Health